1. Field of the Invention
The present invention relates to an intra-vascular device and method. More particularly, the present invention relates to a device for treatment of intra-vascular diseases.
2. Description of Related Art
A conventional main (vessel) stent-graft typically includes a radially expandable reinforcement structure, formed from a plurality of annular stent rings, and a cylindrically shaped layer of graft material, sometimes called graft cloth, defining a lumen to which the stent rings are coupled. Main stent-grafts are well known for use in tubular shaped human vessels.
To illustrate, endovascular aneurysmal exclusion is a method of using a main stent-graft to exclude pressurized fluid flow from the interior of an aneurysm, thereby reducing the risk of rupture of the aneurysm and the associated invasive surgical intervention.
Main stent-grafts with custom side openings are sometimes fabricated to accommodate the particular vessel structure of each individual patient. Specifically, as the location of branch vessels emanating from a main vessel, e.g., having the aneurysm, varies from patient to patient, main stent-grafts are fabricated with side openings customized to match the position of the branch vessels of the particular patient. However, custom fabrication of main stent-grafts is relatively expensive and time consuming.
To avoid custom fabrication of main stent-grafts, side openings in the main stent-graft may be formed in situ. Illustratively, the main stent-graft is placed in the main vessel, e.g., the aorta, to exclude an aneurysm. Fenestrations may be made in situ to correspond to adjacent branches.
The graft material of the main stent-graft is pierced with a needle at the ostium of a branch vessel, e.g., the renal artery, emanating from the main vessel. An expandable balloon is then inserted in the needle perforation in the graft material of the main stent-graft.
A fenestration is typically initiated with a small needle perforation of the graft cloth. The perforation must be enlarged with a conical dilator
However, considerable force is required to expand the balloon and tear the graft material. The application of such a considerable force is difficult to control thus leads to unpredictability in the tear of the graft material or other complications. Further, the branch stent-graft tends to propagate the rent (a split or tear) in the graft material over time. Further, the edge of the rent fractured the branch stent-graft depending upon the particular application. Finally, the edge of the rent was a fray of loose fibers of the graft material, which tended to unwind over time.